floatation

[john_manchester]

Couple of good threads recently on interior layouts, but no mention of floatation.

On the Princess plans there's a floatation chamber under the cockpit. I've been interpreting this as meaning a sealed floatation chamber. But after the discussion around extending a quarter berth under the sole I'm a little confused.

Is floatation optional? Seems like you have to have enough to float the boat when it's full of water, or you may as well not bother. How do you decide whether to include floatation? How do you figure out how much you need?

[wkisting]

Ray, is it true that it's better to put flotation up high?

Somewhere on the 'net I read that higher-positioned foam flotation will have more of a righting effect if the boat should fill with water. That sounds logical IF the whole boat were to roll and completely submerge in a violent knockdown (in which case I suppose the higher the foam and the lower the ballast, the greater the righting effect), BUT... in more realistic conditions, such as if the hull were to breach on a rock, I would think flotation located higher up (say behind the cockpit backrests or up under the side decks) wouldn't do any good until the boat sank low enough to actually submerge the foam, no?

This is a long way of asking: Is there an "ideal" location to place sealed buoyancy tanks or foam?

One last question re: what you said about displacement... if I understand you correctly, you don't need enough flotation to counteract ANY of the wood weight? ONLY the weight of ballast/gear/people needs to be compensated for? Am I understanding correctly?

[john_manchester]

Thanks Ray--that's extremely helpful. Lots of things are not so intuitive for us "lubbers", like the fact that lead displaces water.

Even though a capsize is less likely in a Princess, sounds like I should still plan for having it full of water at some point and adjust the amount of floatation (and junk I stow) accordingly.

Sailing where it's cold (like off the coast of Maine), is there special safety gear you carry to keep you (and your crew) from freezing while trying to bail out the boat (or waiting for help)?

[wkisting]

Wow, thanks Ray! That's a great overview of flotation... better and more instructive than a lot of the dense/diffuse articles I've read online.

28 cu. ft. sounds like a lot. I wonder how much is already included according to plans... some under the cockpit sole, some in the forward bulkheaded compartment, but not sure how many cu. ft. it adds up to be..... Graham, do you know off the top of your head?